1. Field of the Invention
This invention relates to an improved rolling bearing unit which is a part of a rotation support unit (for example, a manual transmission or an automatic transmission of an automobile transmission) for supporting an end portion of a rotation shaft on an inner surface of a housing containing component parts of the automobile transmission.
2. Description of the Related Art
As shown in FIG. 30, an end portion of a rotation shaft 1 such as a counter shaft of an automobile transmission is rotatably supported on an inner surface of a housing 2 accommodating components such as the rotation shaft 1, a gear, etc., through a rolling bearing 3 such as a ball bearing. In this case, an annular or circular holding recess 4 is formed in the inner surface of the housing 2, and an outer ring 5 of the rolling bearing 3 is fitted in the holding recess 4 to be inwardly fixed thereto in an interference manner. The end portion of the rotation shaft 1 is inwardly fitted in the interference manner or the like in an inner ring 6 of the rolling bearing 3 against radial movement. Further, in order to prevent the outer ring 5 from falling off the holding recess 4, the outer ring 5 is held against one axial end face of the holding recess 4 by a retainer plate 7.
Here, the left side in FIGS. 1, 3, 4, 30 and etc., is defined as one axial end, while the right side is defined as the other axial end.
As known, for example, from DE 20019278U1, DE 102005012323B3, JP-T-2007-504412, etc., the rolling bearing 3 and the retainer plate 7 are coupled together to form a bearing unit 8 as shown in FIGS. 31 and 32 so that this bearing unit 8 can be easily mounted in the holding recess 4. In this bearing unit 8; the retainer plate 7 is fitted on a smaller-diameter step portion 9 formed on an outer circumferential surface of the other axial end portion of the outer ring 5 of the rolling bearing 3, and can rotate relative to this outer ring 5.
The rolling bearing unit 8 is mounted within the housing 2 with the outer ring 5 fitted in an interference manner in the holding recess 4 and also with one side face of the retainer plate 7 held against an inner surface of the housing 2. Then, by rotating the retainer plate 7 relative to the outer ring 5, through holes 10 formed through an outer circumferential portion of the retainer plate 7 are brought into alignment respectively with screw holes (not shown) formed in the inner surface of the housing 2. Then, screws are passed through the respective through holes 10, and are threaded into the respective screw holes, and are further tightened. In another structure, instead of the through holes 10, screw holes are formed in the outer circumferential portion of the retainer plate 7, and screws are passed from the exterior through respective through holes formed in the housing 2, and are threaded into the respective screw holes, and are further tightened.
In this structure in which the screw holes are formed in the retainer plate 7, heads of the screws are prevented from projecting into the housing from the retainer plate, and a space within the housing can be efficiently utilized. In either structure, the outer ring 5 is fixedly supported in the holding recess 4 without rattling and also without falling-off from this holding recess 4.
In such a bearing unit 8, the retainer plate 7 is rotatably connected to the outer ring 5, and is prevented from separation from the outer ring 5. The retainer plate 7 is thus rotatable relative to the outer ring 5 so that the through holes 10 and the screw holes can be brought into alignment with each other after the outer ring 5 is fitted in the holding recess 4 in an interference manner or the like against radial movement. Also, the retainer plate 7 is thus not separated from the outer ring 5 so that the rolling bearing 3 and the retainer plate 7 can be handled as a single unit so as to facilitate the management of the parts, an assembling operation, etc.
For these reasons, the outer ring 5 and the retainer plate 7 are connected together so as to rotate relative to each other but can not be separated from each other. Therefore in the structure described in DE20019278U1, a plurality of projections formed on an inner circumferential edge of the retainer plate are engaged in a circumferential recess formed in an outer circumferential surface of the smaller-diameter step portion. In the structure described in DE102005012323B3, the side face of the retainer plate is held by a leaf spring held on an outer circumferential surface of the smaller-diameter step portion. Further, in the structure described in JP-T-2007-504412, an inner circumferential edge of the retainer plate is plastically deformed, and is engaged in a circumferential recess formed in an outer circumferential surface of the smaller-diameter step portion.
In the structure described in DE20019278U1, when a strength of connection between the outer ring 5 and the retainer plate 7 is increased, an operation for engaging the projections in the circumferential recess becomes difficult. Particularly, when the thickness and resiliency of this retainer plate 7 are increased so that the retainer plate 7 can retain the outer ring 5 in the holding recess 4 with a large force, the above difficulty becomes conspicuous. In the, structure described in DE 102005012323B3, although such a disadvantage is not encountered, the cost is inevitably increased since the leaf spring complicated in shape and requiring cumbersome processing or working is used. Further, in the structure described in JP-T-2007-504412, a pressing machine for plastically deforming the retainer plate is required, and therefore the cost is increased.